MECHANICAL RABBIT
Independent Project, 2020
While quarantining last summer, I wanted to build something, but did not have access to a shop or much equipment. I decided to start my own project incorporating mechatronics and art. I was inspired by wind-up toys, and the unique ways in which they can move. I decided to design and build a small, motorized rabbit using kinematic synthesis tools to design a linakage system that mimics the motion of a rabbits hop! I started with this sketch of each main position of a rabbit throughout its stride.
Analyzing the Coupling Curve
Pictured is an analysis I did on the coupling curve (path of the linkage, or foot in this case) using a clip of a rabbit hopping. I imported the clip as separate frames into GIMP and traced the foot path and position with the spline tool.
Kinematic Synthesis
I based my four-bar linkage on Chebyshev's Lambda Mechanism, which is moves in a straight line at a constant velocity for half the time, and then accelerates. I modified this mechanism in a CAD software called Linkage. By lengthening the third and fourth bar, I was able to create a linkage that followed a triangular coupling curve, more similar to a rabbit's hop. I utilized the acceleration for when the rabbit launches itself off the ground. If this force is not enough, I may consider adding a spring for extra thrust in the hop.
Prototyping
Using cardboard and dowel rods, I modeled my four-bar mechanism, which you can see to the right. I found that extra friction at the feet will be essential to making sure the rabbit gains traction in its hop. Balance is also key; I plan on gearing up a toy motor to see how the location of the center of mass affects how this prototype works.
